Structural and Magnetic Studies in Ni-Mn-Ga based Ferromagnetic Shape Memory Alloys

R. P. Mathur; R. K. Singh; S. Ray; M. Manivel Raja; P. Ghosal; V. Chandrasekaran

doi:10.14429/dsj.61.645

R. P. Mathur Defence Metallurgical Research Laboratory, Hyderabad
R. K. Singh Defence Metallurgical Research Laboratory, Hyderabad
S. Ray Indian Institute of Technology Roorkee, Roorkee
M. Manivel Raja Defence Metallurgical Research Laboratory, Hyderabad
P. Ghosal Defence Metallurgical Research Laboratory, Hyderabad
V. Chandrasekaran Defence Metallurgical Research Laboratory, Hyderabad

DOI: https://doi.org/10.14429/dsj.61.645

Keywords: Ferromagnetic shape memory alloys, Ni-Fe-Mn-Ga alloys, Martensitic transformation, Mössbaeur spectroscopy

Abstract

Quaternary Ni50FexMn30-xGa20 (x = 2.5, 5, and 15) and Ni45Fe5Mn30Ga20 alloys based on modification of ferromagnetic shape memory alloy ternary Ni50Mn30Ga20 composition prepared by vacuum arc melting and subsequent heat-treatment were investigated to understand the effect of varying Fe-content in Ni-Fe-Mn-Ga alloys. With increasing Fe-content, saturation magnetisation and Curie temperature increased, however martensite transformation temperature did not show a systematic variation. The 57Fe Mossbauer spectra showed three distinct sub-spectra depending upon the site occupancy by Fe-atoms. The results are explained with site selection by Fe-atom in parent L21 lattice.

Defence Science Journal, 2011, 61(3), pp.275-284, DOI:http://dx.doi.org/10.14429/dsj.61.645